What happens in the end of Shutter Island? There’s a huge plot twist: Teddy isn’t actually Teddy, nor is he a U.S. Marshal. Teddy is Andrew Laeddis, a demented killer and a patient in the mental hospital he’s “investigating.” His psychiatrist has encouraged Andrew to act out his delusions.

The implausible escape of a brilliant murderess brings U.S. Marshal Teddy Daniels (Leonardo DiCaprio) and his new partner (Mark Ruffalo) to Ashecliffe Hospital, a fortress-like insane asylum located on a remote, windswept island. The woman appears to have vanished from a locked room, and there are hints of terrible deeds committed within the hospital walls. As the investigation deepens, Teddy realizes he will have to confront his own dark fears if he hopes to make it off the island alive.
Shutter Island/Film synopsis

Unfortunately, “Shutter Island” isn’t based on a true story, and author Dennis Lehane came up with the mystery of his own accord — however, that doesn’t mean there aren’t elements of truth thrown in for good measure. It’s widely known that Lehane based the titular island of the story on Long Island in Boston Harbor.

Despite this, the film does stay relatively true to the book. Ease of viewing is increased for those who read it beforehand, as they are already familiar with the developments occurring on-screen. There is, however, one significant difference between the novel and the film concerning its ending.

However, what we really see transpire is Teddy choosing to be lobotomized. The doctors’ aggressive role play actually worked—just not in the way they had hoped. Teddy does, in fact, remember that he burnt down his apartment building and killed his wife.

“Shutter Island” stars DiCaprio as Edward “Teddy” Daniels, a U.S. Marshal who is investigating a psychiatric facility on the eponymous island after a patient goes missing. Only Teddy is not a real person but a delusion created by inmate Andrew Laeddis.

Dr Cawley (Ben Kingsley) explains that the “Law of 4” refers to the fact that two names are anagrams. They are: (1) Dolores Chanal (Andrew’s wife’s maiden name) rearranged to Rachel Solando and (2) Andrew Laeddis rearranged to Edward Daniels.

The ending of “Shutter Island” reveals that DiCaprio’s character is a patient himself, committed to the Shutter Island facility after murdering his wife (Michelle Williams) because she went insane and killed their children.

“The law of 4” is basically an algebraic reference to both the anagrams, Edward Daniels and Rachel Solando (4 scrambled names in all), who are fictional characters. While “the law of 4” indicates that the 4 names are anagrams, “who is 67?” is a clue as to Andrew’s identity.

The Rule of 4 and Patient 67 “Edward (Teddy) Daniels” is an anagram of “Andrew Laeddis” and “Rachel Solando” is an anagram of “Dolores Chanal,” the maiden name of Andrew’s dead wife.

Shutter Island. Lehane was inspired by the hospital and grounds on Long Island in Boston Harbor for the model of the hospital and island. Lehane had visited it in the Blizzard of 1978 as a child with his uncle and family.

Shutter Island is a 2010 American neo-noir psychological thriller film directed by Martin Scorsese and written by Laeta Kalogridis, based on Dennis Lehane’s 2003 novel of the same name. Leonardo DiCaprio stars as U.S. Marshal Edward “Teddy” Daniels who is investigating a psychiatric facility on Shutter Island after one of the patients goes missing.

Shutter Island was mainly filmed in Massachusetts, with Taunton being the location for the World War II flashback scenes. Old industrial buildings in Taunton’s Whittenton Mills Complex replicated the Dachau concentration camp.

Shutter Island is an American Psychological Film that expresses a lot of disorder and dissociative identities disorders, especially from the main character of the movie, Leonardo DiCaprio .